Slide projector with mechanical feed



Jan. 26, 1960 E. KRULL 2,922,334

SLIDE PROJECTOR WITH MECHANICAL FEED Filed Feb. 21, 1956 2 Sheets-Sheet 1 'A BBT ERNST KRULL ray/6MM@ ATTORNEYS Jan. 26, 1960 E. KRULL 2,922,334

SLIDE PROJECTOR WITH MECHANICAL FEED Filed Feb. 2l, 1956 2 Sheets-Sheet 2 INVENTOR ERNST KRULL BY Mg/M2@ ATTORNEYS SLIDE PROJECTOR Wrrrr MECHANICAL FEED Ernst Krull, Essen, Germany, assignor to Agfa VAktiengesellschaft, Leverkusen, Germany, a corporation of 'Germany This invention relates to a slide projector including a mechanical slide-changing device for continuous sequential demonstration of lamellar diapositives, otherwise known as transparencies, from compartments of a storage container and return thereto; and more particu-A larly to a projector of this type in which the storage container is intermittently advanced forward the distance of a compartment by a feed mechanism.

Various mechanical slide-changing devices have been adapted to slide projectors. In one of these known mechanicalslide changers the storage container is supported on a T-shaped 4frame which is inserted through the projection aperture. A sliding frame is used. to guide the individual transparencies into the projection aperture. Thetransparencies are inserted in compartments in a box-like storage container. The transparencies are slid from their compartments in pockets provided bythesliding frame .into the projection position and then back into the compartment. A sliding bar is provided including a projection which moves the frame to and fro. In addition to the fact that the transparencies must be inserted into the pockets of the frame, there is 'anotherdisadvantage in that the unbalanced weight of the compartment and the off-center actuation of the slide-changing lever tend to disturb the steadinessV of the projector mounting. `This very-often causes lthe projected image to' be'displaced requiring frequentadjustrnent of the projector.'

There are also mechanical slide-changing devices in nited Sttes Patenti() which thestorage container is mounted in achamber inthe side of the projector housing. This `container Vhas a vslotted bottornand is rotated 90 when it is inserted for operation into the projector to turn the' open top of the compartment toward the projector. Since the individual transparencies slide freely in their slots, or compartments, special care must be taken during rotation of the container so that the transparencies which may `slip out of their compartment during rotation are moved carefully back into their original position in the compartment. Otherwise Ithe cardboard-'frames Iof thetransparencies may be broken. The arrangement of -the storage container in the side of-the housing also makes the housing` relatively wide,- lngoperation the back and forth movement of `the transparency slider, which moves at an angle to the optical axi s,tends to cause disturbing movement of the projector and image. 'i j Finally there are known projectors of the type in which a transparency Container is carried in a channel beneath the lamp housing.`

These transparencies are` lifted into the-position for projection by a sliding member o-r slider ,whichpassesthrough an `.opening in the container bottom. This slider is moved np and down by a slider-Crank rmechanism. `This slider-crank ymechanism engages in teeth provided on the bottom of the storage v container and moves it-` forward the distancejbetween compartmentsfstep-by-step.V This type of `construction requires a great deal of space .under the lamp housing corresponding to the length of travel ofthe slider-crank vcation of unbalanced forces to the projector.

age container is mounted in a channel beneath the lamp:

4 fastened to this endless belt.

2,922,334 Patented Jan. ze, 1960 mechanism, and this mechanism is also complicated and expensive. Since the base ,ofthe housing usually does not provide much clearance height, this mechanism must be positioned to move into a higher portion of the housing during certain portions of its operative cycle.

l in accordance with this invention a projector including a mechanical slide-changing device is provided whose size inherently remains compactly within the limits of an ordinary projector housing, and in which the driving movement of the transparency slider occurs as close as possible to the optical axis. This inherentlyeliminates the appli- The storhousing. The transparencies are lifted or raised by a slider which engages them through the slotted bottomwall of the container. The transparencies are positioned in front of the projection aperture and then returned into their compartment in the container. The container .is

then moved forward by means of an actuating lever which moves the container forward a distance `equal to a compartment. In accordance'with this invention the slider is a curved steel band which is bent around a curved surface which is disposed at the front end of the projector housing. The turning point provided by the curved surface is preferably provided in the form of a roller. The driven end of the slider is thereby deected at an angle to the plane of the transparency guide.

1n this arrangement the portion of the steel band which moves t0 the upper end of the transparency guide is stiii`- ened by being warped to form a curved cross section. Portions of-the band on either side of the turning point may` beso warped to be stiifened. In a simple embodiment of this invention, the driving end of the band, remote lfrom the storage container,V is joined to a driving mechanism by means of which this end of the band is moved in a substantially straight line to-and-fro in a direction parallel to the optical axis. This driving means can, therefore, be positionedparallel to the optical axis and it can, therefore, protrude through the rear wall of the projector base. A driving lever may be arranged, however, rotatably mountedon the walls of, the projector. The slider can then be operated by a handwheel provided on the right or leftfside of the housing. i

In another form' of this invention, the end of the steel provided Within the housing rotating about a pair 0f rollers. The driving end ofthe band-shaped slider is This endless belt is driven back and forth by the rotatable handwheel which is coupled to arrigid lever whoserernote end is attached to the upper portion of the endless belt. p

Spring ngers are disposed to bear against thesurface of the projection aperture. These springs are actuable to allow free entry of the transparency into the projection position.` This permits free movement of the transparency into vthe lexact predetermined position lfor projection.

Means are provided for momentarily pressing the transe parencyrmly in contact with the surface of theprof` jection aperture While a rotatable dimmer is swung out of the path of the light rays. The sideof ythe dimmingA plate adjacent the projection aperture is extended past 3 its` pivot to press the 'springagainst the transparency when the dimming platevis swung out of the path of the light rays. This dimming plate is coupled with a slotted y inserted'in vertical compartments 12ay provided between sliding arm which is coupled to the dimmer by means of i a connectin'grod.- The dimmingplateis4 therebyrotated byv lateral-movement-of the slidingarm.- v

A llocking lever is provided for holding.y the-storage containerimmovable during the act ofvraising and lowering each transparency. This lockinglever has-aflat upwardlyv bent end which engages teeth or slots provided in the bottom of the storage compartment. This locking lever includes a slanted surface/Jon its -rear end. The driving lever moves against this surfacel to drive the locking 1lever downward to disengage-A-it froma tooth in the storage containerfto allowth'estoragecontainer to movelforward when the. driving vlever. has-retracted the slider. The .at upwardlyubent-iendof a latch initially limits vthe forward=movernent of-ftheafstoragek containerwheneitis inserted into the channelfand italso'later actuates Vthe container to providesuccessivepositionsy ofthe storage compartments... A -ldouble-endedlever is rotatably mounted on the side-wall .of the housing This double-ended lever carriesthe aforementionedflatch which is .rotatably coupled to its lowery end. .This .latch includes va flat upwardly bent end .which engages the. teeth.. provided along the bottom of thestorage container.t This latch -is moved to the tooth in back ofy thev tooth engagedv by the locking lever when the free end ofthe double-ended lever is actuated by movement of the driving lever in position to raise the transparency to its projection position..` When the driving lever moves to restore the transparency to its compartment, it disengages the locking lever which permits the latch to be pulled forward by a spring to move the storage container forward the distance of one toothwhich corresponds to the distance between transparencies or-compartments.

The aforementioned rotating dimming plate may be4 eliminated byproviding. a dimming plate sliding in front of the projection aperture. This dimming platemay be formed, similarly to an iris diaphragm, of overlapping sliding strips which are coupled end to end.

This invention is basically independent of many of I the aforementioned details. y Instead of thesliding curved steel band movingy to-and-,fro within coniining guides, a slider might be formed, forjexample, `bynarrovv ribbons wound at an angle to the direction of movement in a manner similar to that provided Vin a roller window blind. These ribbons might be guided through the compartments of the storage container by U-shaped guide grooves pro-` vided in ytheside walls of the compartments.

Novel features and advantagesof the present invention will`become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings in which:

Fig. 1is across-sectional view in elevation of one embodiment in this invention;

Fig. 2 is a View in elevation of the embodiment shown in Fig. l partially brokenaway; and

Fi'g.,3 is a're'ar view in elevation Vof the'embodiment i shown'in Figs. l and 2.4

The housing includes in the lamp chamber 2 "an optical system. This optical ysystem includes a reflector 3. a lamp 4,"and condenser lenses 5 and 6, which are arranged behind the projection aperture 7 in the vertical wall S. The objective lens '9 is subsequently positioned along the optical axis. A horizontal chamber 11 is provided under the horizontally positioned partition 10 of insulating material. This partition 10 incooperation with vertical wall d lsegregates the'lamphousevz accom modatngthe transparency container 1,2. The ends of chamber 11 are dened by two large openings in the housing' 1. The storage Vcontainer '12 rides parallel to thev opticalY axis of lens 9 on a horizontal plate 13a 'which ribs 12b on its longitudinal sidewalls. A longitudinal slot is provided running down the center of the contamer bottom 12e. This permits a fork-shaped end 14a of a slider 14, in each sequential position of the container' 12, to push the transparency 15 lying above it upward 1nto the projection position. Movement of the transparency is guided by the' contacting fronti surface o f` the Wall 8 and the guiding strips 16. Strips 16 are positioned away from wall 8 a distance slightly greaterv than the thickness ot the transparency.

The slider iftconsists of a exible steel band, extended portions of which are slightly warped to provide stitness.

An endless belt 19 is looped about rollers 17 and 18. An end of the steel band 14` is fastened to the endless belt 19 at 28. Extendedportions of thezstee'hband 14 are confined within a channel 21, to warp it or bend its edges towards each other to form a C-shaped cross section. The stitiness of thel band 14":is, therefore, only-alleviated at the turning point provided by'the curved surface of the roller 17. Movement of the slider 14 accordingly occurs by means of'backward and forwardmovement of the endless belt 19: A bar or coupling -1501is provided on the upper traverse yof 'thet endlessr'belt. This coupling 5() may betmoved through a horizontallslotin the bottom of the housing base 13,- or throughalslot'iextendmg through the back wall'of thebas 13.' Ina preferred device7 shown in Figs. l, 2 and 3 a'handwheel23 is rotatably supported in a pivot 22'on theside wall yof-the housing 1 or on an inside wall' which is parallel 4'to it. This'handwheel 23 is rigidly'coupledto a lever A24 lwhose end 24a is joined'to the upper/traverseofthefendless belt 19 by means of coupling 50. Lever --24 may1be formed as a U-shaped frame rotatably mounted on-both sides of the lamphouse to stably guide the 'coupling 50'to whlch the endless belt 19is fastened. The elasticity-*provided by the endless belt absorbs the -Amovement of lever end 24a on' its curved vpath and-'transfonns it to substantially straight reciprocatingmovement of thelslider 14.

In front of the projection aperture-7 inthe wall 8 1n the zone Where the two vertical edgesoff thelifted transparency 15 are positioned, two spring-ngers 25 are fastened." These fingers A25 are shapedito press closely against the surface ofthe projectionaperturej Dimmmg plate 27 is` rotatably mounted on pin-27a which is held Vby bracket 26. The end'27b ofthisdi'mmng plate 27 is extendedpast theaxis 27d tofcontact the spring 25 when dimrnigfplatef27 is swungupward out of the path of the light rays. This swung-out yposition is shown in broken line -in Fig'. 2.- Sp'ringsf-'ZSJare thereby caused to pressl the lifted transparency ISti'glitly against the appropriatel'surfaceofthefprojectionaperture in wall 8. The-'rotation of#- this dimming plate'27-about the axis 27aftakes^p1aceby meansof a connecting rod 27C, coupled to'a slidin'g v'arm-'28 which is mounted on the housing by meanszof la isucrewan'd, washer'29V inserted through s1ot'28ar` Thefend28b of the'. arm 28 is 4shaped at an angleto be contacted and moved by the extension 24b of thedriving-lever 24'which strikesit-at the end of a stroke' ofthe lever 24 when the transparency is lifted into its projection position. The dimming plate-27 opens againstl'oading by a return spring notl shown, in the drawing. The base 12e of storage container 12 includes a laterally projecting ange 12d lwhich `engages a groove (not shown) to prevent it from rising. A rack of squaretoothed gearing provides a series of teeth 12e on the bottomof the storage container 12. These teeth are positioned apart thev distance vbetween transparencies in their compartrnent's'.Y A locking lever 3.1 is rotatably'mo'unted about a shaft 'tixedlin'the'base 13 of the housing. Locking 'lever 31"incl`ude's ariA upwardtu'rned Hat end or extension 31a'. This projectionla engages the successive teeth of the storage `container to arrest its travel as it moves throughthe housing; This `locking lever 31 is urged'upwardA into the locking' `position by means `of a @bassi l spring (not shown). One, therefore, can push the container 12 forward until the first transparency 15 is automatically positioned over the slider 14 by means of latch 32 (later described). The `end `31a remains engaged in the tooth until it is rotated downward'by contact of the roller 24C of the driving lever 24 on the slanted surface 31b on the end of lever 31. Driving lever 24 disengages end 31a of lever 31 from a tooth 12e when the lower end of lever 24 is thrust forward moving the forked end 14a of slider 14 down and out of the path of movement of storage container 12 thereby restoring the transparency to its compartment. Complete safety of operation is, therefore, assured because the storage container is not unlocked unless slider 14 is fully retracted' out of the path of its forward movement.

A spring-operated push latch 32 is rotatably mounted about a pin at the bottom of double-ended lever 34. This double-ended lever 34 is rotatably mounted about a 4pin 35 which is fixed in a vertical side wall of the housing. The upper end 34a of lever 34 terminates with a roller 34b which projects into the path of movement of the end 24h of driving lever 24. The free end 32a` of the latch 32 slants upward to engage the teeth 12e at an angle to permit latch 32 when moved backward to momentarily overcome the forward pull of tension spring 36 and ride over a tooth 12e and engage in the next tooth space. Slanted end 32a also arrests the first tooth of the storage container as it is inserted into the housing automatically position the first transparency over the slider 14. The container 12 andthe spring loaded lever 32 remain blocked in this locked position by upwardly bent extension 31a which remains engaged in the initial tooth space until after the retraction of the slider 14 by driving lever 24. When the roller 24e of driving lever 24 drives end 31b of the locking lever,.31 downward to withdraw locking extension 31a from this initial tooth-space, this permits latch 32 to be pulled forward by the spring 36 thereby moving the storage container forward the distance of one tooth or compartment. The next transparency is thereby placed into position for raising and projection.

What is claimed is:

1. A slide projector for continuous sequential demonstration of transparencies from compartments of a storage container by means of a slider mechanism which contacts the transparencies through slots in a side of said container which is intermittently advanced, said slider mechanism comprising a flexible band, a curved surface mounted in the projector housing and positioned in the path of movement of said slider, said flexible band turning a corner about said curved surface from its substantially longitudinal path of movement through said housing to its relatively substantially perpendicular path of movement through a compartment of said storage container, channel means confining the portion of said band extending through said storage compartment to warp it in cross-section to stilfen said portion of said band, a shoe for engaging transparencies fastened to the end of said band passing through storage compartment, translating means coupled to the end of said steel band remote from said storage container for imparting movement to said remote end of the flexible band for removing transparencies from said storage compartments into position for projection and subsequent return to said storage compartment, said flexible band being confined within said channel means on both sides of said curved surface, an endless belt rotatably mounted in said projector housing adjacent the path of movement of the end of said flexible band remote from said storage container, attaching means fastening said end of said flexible band to a point on said endless belt to guide and cause the backward and forward movement of said portion of said flexible band, driving lever rotatably mounted on a wall of said projector housing, said endless belt including 6 a coupling means, an end of said lever being joined to said coupling means to provide backward and forward motion of said endless belt to reciprocate said attached slider, a manually operable means joined to said lever to allow said lever to be easily moved backward and forward by hand, said projector housing including a front wall including a projection aperture, a pair of spring fingers contacting the surface of said projection aperture, an end of each of said spring fingers being secured to said wall, a rotatable dimmer plate being hinged to said Wall adjacent the hinged end of said spring fingers, said dimmer plate including an extension for` contacting a portion of said spring fingers for firmly pressing said spring fingers against a transparency raised in projection position against said surface of said projection aperture, said dimmer plate being coupled to a sliding arm by means of a connecting rod, said sliding arm including a slot, said slotted portion .of said sliding arm being loosely mounted upon said projector housing by pin means passing through said slot, and said sliding arm being disposed in the path of movement of an end of said driving lever to cause said dimmer plate to be raised and said spring fingers to be pressed against a raised transparency when said driving lever has been rotated in position to move` said slider in position to move a transparency into the projection position.

2. A projector as set forth in claim 1 wherein a series of teeth are provided in a side of said storage container, said teeth being spaced apart the distance between transparencies in said compartments, a locking lever is rotatably mounted in the base of said housing, said locking lever includes an extension for engaging said teeth, said locking lever also including an actuating surface, said driving lever including a projection for contacting said actuating surface to dn've said locking lever downward to designate said extension from said teeth to permit said storage container to be driven forward when said driving lever has rotated said flexiblel band into its retracted position clear of the path of movement of said storage container. i Y

3. A projector as set forth in claim 2 wherein a doubleended lever is rotatably mounted upon said housing, a

push latch is rotatably coupled to the lower end of said double-ended lever, said latch includes a bent extension for engaging said teeth, a tension spring anchored to said housing and secured to the end of said latch to draw said latch in a forward direction, said latch bent extension being shaped to permit said latch to be drawn backward from the tooth engaged by said locking lever to the adjacent tooth, said ydouble-ended lever including a projection at its upper end lying in the path of movement of the upper end of said driving lever for moving said latch backward the distance of one of said teeth when said driving lever is rotated to cause said slider to raise a -transparency into said projection position, and said tension spring drawing said push latch forward to advance said storage container the distance of one toothV when said locking lever is disengaged from the adjacent tooth by rotation of said driving lever to its position to retract said slider and restore said transparency to its compartment;

4. A slide projector for continuous sequential demonstration of transparencies from compartments of a storage container by means of a slider mechanism which contacts said transparencies through slots in a side of said container, said slider mechanism comprising a flexible band, a curved surface mounted in the projector housing and positioned in the path of movement of said slider, said flexible band turning a corner about said curved surface from its substantially longitudinal path of movement through said housing to a path of movement disposed substantially perpendicular thereto and passing through a compartment of said storage container, channel -means confining the portion of said band extending through said storage compartment for warping it in cross-section to stilfen said portion of'said band, a shoe for engaging transparencies fastened to the end of said band passing through said storage Compartment, translating means coupled yto the end of said exible band remote from said storage container for imparting substantially longitudinal ,movement to said eXible band for removing transparencies fromv said storage .cbmpiaftments into position for projection and vsubsequent fretnrn to said storage compartment, a movable contrtgl means mounted upon said projector housing, connecting means operatively coupling said movable control ,means `to said translating means, a series of teeth provided .upon a side of said storage container, said ,teeth 'being spaced apart a distance corresponding to ,the distancey between transparencies in said compartments, a locking llever movably mounted within said housing, said locking lever including an extension Vfor engaging said teeth, coupling means operatively engaging said movable lcontrolfmeans with said locking lever and-being yconstructed and Varranged for disengaging said extension from said teeth when said movable control means has moved said llexible band into its retracted position clear of the path of movement of said storage container to permit said storage container to be driven `forward to .the position for removing and demonstrating the next transparency, said movable control means comprising ,a driving lever, a double-ended lever `being rotatably mounted upon said housing, a push latch being rotatably ,coupled to the lower end of said double-ended lever, -said l,latch including a bent extension for engaging said teeth, a ,tension spring anchored to said housing and secured to the end of said latch to draw said latch in a forward direction, said bent extension being shaped to permit said ,latch to be drawn backward from the tooth engaged by said locking lever to the adjacent tooth, said double-ended lever including a projection at its upper end lying in the path of movement of the upper end of said driving lever for moving said latch backward the distance'of one of said teeth when said driving lever is rotated `to cause said slider to raise a transparency into said projection position, and said tension spring drawing said push latch forward to advance said '..Storage container the distance of one tooth when ysaid locking lever is disengaged from the adjacent 'tooth by Irtationfof said driving lever to a position at vwhich it re/tracts" ysaid .slider and restores said transparency to ,its cbrnpartment."

5. A projector as -set forth in claim 4 wherein said flexible bandlis confined within said channel means on both sides of said'curved surface.

6. A projector as set forth in claim 4 wherein an endless belt is rotatably mounted in said projector hou."- ing adjacent the path vof movement of the end of said flexible band remote from said storage container, attaching means fastening said end of said flexible band to a point on said endless belt to guide and cause the backward and forward movement of said portion of said flexible band.

7. A projector as set forth in claim 6 wherein a driving lever is rotatably mounted on a wall of said projector housing, said endless belt including a coupling means, an end of said lever being joined to said coupling means to provide lbackward and forward motion of said endless belt to reciprocate said attached slider, and a manually operable means joined to said lever to allow said lever to be easily moved backward and forward by hand.

References Cited in the file of this patent UNITED STATES PATENTS 594,819 Allen NOV. 30, 1897 1,624,098 ,Goldsmith et al Apr. 12, 1927 2,132,716 Wittel Oct. 11, 1938 2,276,935 Corno Mar. 17, 1942 2,401,506` Pechkranz .lune 4, 1946 2,528,325 Valpey Oct. 3l, 1950 2,579,281 Tuck Dec. 18, 195,1

FOREIGN PATENTS 347,782 France Jan. 17, 1905 408,237 France Jan. 19, 1910 

